OARD 


LIBRARY 
STATE  PLANT  BOARD 


Circular  No.  127. 


Issued  December  7,  lyiO. 


r    United  States  Department  of  Agriculture, 


INSECT  INJURIES  TO  THE  WOOD  OF  DYING  AND  DEAD 


Timber  dying  from  insect  attack  and  other  causes,  including  fire, 
disease,  storms,  etc.,  is  attacked  by  certain  wood-boring  insects  which 
extend  their  burrows  through  the  sound  sapwood  and  heartwood,  and 
thus  contribute  to  the  rapid  deterioration  and  decay  of  a  commodity 
which  otherwise  would  be  available  commercially  during  periods  of 
from  one  to  twenty  years  or  more  after  the  death  of  the  trees,  depend- 
ing on  the  species  of  trees  and  on  the  character  of  the  product  desired. 
This  loss  often  amounts  to  from  25  to  100  per  cent  during  the  period 
<•  in  which  the  dead  timber  would  otherwise  be  almost  as  valuable  as  if 
living. 


Sawyers. — One  of  the  most  striking  examples  of  the  destruction  or 
deterioration  of  the  wood  of  dying  and  dead  timber,  familiar  to  all 
lumbermen,  is  the  injury  to  fire-killed  and  storm-felled  pine,  fir, 
spruce,  etc.,  caused  by  boring  larva?  known  as  "  sawyers."  These 
borers  hatch  from  eggs  deposited  by  the  adult  beetles  in  the  bark  of 
the  dying  trees,  and  after  feeding  on  the  inner  bark  for  a  time  they 
enter  the  solid  wood  and  extend  their  large  burrows  deep  into  the 
heartwood.  Fire-killed  white  pine  is  especially  liable  to  this  injury, 
and  is  often  so  seriously  damaged  within  three  or  four  months  during 
the  warm  season  as  to  reduce  the  value  of  the  timber  30  to  50  per  cent. 
The  shortleaf,  loblolly,  and  longleaf  pines  of  the  Southern  States  are 

a  Revised  extracts  from  Bulletin  No.  58,  Part  V,  Bureau  of  Entomology,  U.  S. 
Department  of  Agriculture,  1909. 
64138°— Cir.  127—10 


BUREAU  OF  ENTOMOLOGY. 


L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 


TREES.0 


By  A.  D.  Hopkins, 
In  Charge  of  Forest  Insect  Investigations. 


CONIFEROUS  TREES. 


2 


IXSECT  INJURIES  TO  WOOD  OF  DYIXG  AXD  DEAD  TREES. 


damaged  to  a  somewhat  less  extent,  but  instances  are  known  in  which 
more  than  one  billion  feet  of  storm-felled  timber  within  limited  areas 
were  reduced  in  value  25  to  35  per  cent  within  three  months  after  the 
storm.  The  fire-killed  and  insect-killed  sugar  pine,  silver  pine,  and 
yellow  pine  of  the  western  forests  are  also  damaged  in  a  similar  man- 
ner and  the  value  of  the  product  greatly  reduced  within  a  few  months 
after  the  trees  die.  The  aggregate  losses  from  this  secondary  source 
in  the  coniferous  forests  of  the  entire  country  contribute  largely  to  the 
annual  waste  of  millions  of  dollars'  worth  of  forest  products  which 
otherwise  might  be  utilized. 

Ambrosia  beetles. — "Wood-boring  insects  of  another  class,  known  as 
timber  beetles  or  ambrosia  beetles,  cause  pinhole  defects,  principally 
in  the  sapwood,  although  some  of  them  extend  their  burrows  into  the 
heartwood.  These  insects  make  their  attack  in  the  early  stage  of  the 
declining  or  dying  of  the  tree,  or  before  the  sapwood  has  materially 
changed  from  the  normal  healthy  condition,  and  often  in  such  num- 
bers as  to  perforate  every  square  inch  of  wood.  Thus  the  wood  is 
not  only  rendered  defective  on  account  of  the  presence  of  pinholes, 
but  the  holes  give  entrance  to  a  wood-staining  fungus  which  causes  a 
rapid  discoloration  and  produces  still  further  deterioration  of  the 
product. 

The  sapwood  of  trees  dying  from  the  attack  of  other  insects  or 
from  fire,  storm,  or  other  causes  is  often  reduced  in  value  50  per  cent 
or  more,  and  in  some  cases  the  value  of  the  heartwood  is  reduced  in  a 
like  manner  from  5  to  10  per  cent. 

Pinhole  borers  in  cypress. — An  example  of  the  destructive  work 
of  insects  which  attack  dying  and  dead  trees  is  found  in  the  cypress 
in  the  Gulf  States,  where  these  trees  are  deadened  by  the  lumbermen 
and  left  standing  several  months,  or  until  the  timber  is  sufficiently 
dry  to  be  floated.  Upon  investigation  it  was  found  that  trees  dead- 
ened at  certain  seasons  of  the  year  were  attacked  by  the  ambrosia 
beetles,-  or  pinhole  borers,  and  that  in  some  cases  millions  of  feet  of 
timber  had  been  reduced  10  to  25  per  cent  or  more  in  value.0 

HARDWOOD  TREES. 

Round  headed  borers,  timber  worms,  and  ambrosia  beetles. — The 
principal  damage  to  dying  and  dead  hardwood  trees  is  caused  by  cer- 
tain roundheaded  wood-borers  (Cerambycidse)  with  habits  similar  to 
the  sawyer,  by  the  timber  worms  mentioned  as  damaging  living  tim- 
ber, and  by  ambrosia  beetles  having  habits  similar  to  those  that  attack 
the  sapwood  and  heartwood  of  conifers.  All  of  the  hardwoods  sutler 
more  or  less,  but  the  greatest  damage  is  done  to  the  wood  of  hickory, 

"  For  met  hods  of  preventing  pinhole  injury  to  girdled  cypress  sec  Circular  .No. 
82  of  the  Bureau  of  Entomology,  U.  S.  Department  of  Agriculture. 
[Clr.  127] 


INSECT  INJURIES  TO  WOOD  OF  DYING  AND  DEAD  TREES. 


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ash,  oak,  and  chestnut,  which  are  often  reduced  in  value  10  to  25  per 
cent  or  more  within  the  period  in  which  it  would  otherwise  remain 
sound  and  available  for  commercial  purposes. 

PREVENTION  OF  INJURY  TO  DYING  AND  DEAD  TREES. 

A  large  percentage  of  the  injury  to  the  wood  of  insect,  fire,  and 
lightning  killed  trees  and  those  killed  or  dying  from  injuries  by 
storms,  disease,  etc.,  can  be  prevented  as  follows : 

(1)  By  the  prompt  utilization  of  such  timber  within  a  few  weeks 
or  months  after  it  is  dead  or  found  to  be  past  recovery. 

(2)  Ity  removing  the  bark  from  the  merchantable  portions  of  the 
trunks  within  a  few  weeks  after  the  trees  are  dead  (the  work  to  be 
done  either  before  or  after  the  trees  are  felled). 

(3)  By  felling  the  trees  and  placing  the  unbarked  logs  in  water. 

(4)  By  the  adoption  of  a  system  of  forest  management  which  will 
provide  for  the  prompt  utilization  of  all  trees  which  die  from  any 
cause. 

Approved : 

James  Wilson, 

Secretary  of  Agriculture. 

Washington,  D.  C,  October  7,  1010. 

[Cir.  127] 


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